Internal combustion engine control systems



Sept. 1, 1959 A. BIERMANN 2,902,013

INTERNAL COMBUSTION, ENGINE CONTROL SYSTEMS v Filed May 20, 1957 v 4Sheets-Sheet 1 35 38 37 8 POWER 9 IO 6 lDl-E BRAKING INCREASING STROKEl5 l6 l4 0 FOOT-FREE 1 3 BRA KING ADJUSTMENT m 32 STROKE INCREA SED BYINCPEA SE OF ENG/NE TORQUE INVENTOR.

Sept. 1, 1959 A. E. BIERMANN 2,902,013

INTERNAL COMBUSTION ENGINE CONTROL SYSTEMS Filed May 20, 1957 4Sheets-Sheet 2 9 BRAK/NG 66 1o 6 INCREASING I STROKE I3 PRESSURE REG ULA TOP DASHBOARD F0 0 T +7255 E3 BRAKING ADJUSTMENT INVENTOR.

A. E. BIERMANN I INTERNAL COMBUSTION ENGINE CONTROL SYSTEMS Filed May20, 1957 Sept. 1, 1959 4 Sheets-Sheet 3 POWER IDLE BRAK/NG INCDE A SINGS TROK E F00 T-F/QEE BRAKING ADJUSTMENT PRES SURE PEGULA TOR IN VEN TOR.

Sept. -1, 1959 A. E. BIERMANN 2,902,013

INTERNAL COMBUSTION ENGINE CONTROL SYSTEMS Filed May 20, 1957 4Sheets-Sheet 4 E OPEN i z f CONF/GJ CONF/G. a THRO TTLE CONF/G. 2OPENING Q I F\// G CL OSED MA X IMUM P/STON I S TROK E CONF/G..2 ZEROENG/NE P0 WE R BRAKING RANGE RANGE gg g INVEN TOR.

United'States Patent Ofifice 2,902,013 Patented Sept. 1, 1959 INTERNALCOMBUSTION ENGINE CONTROL SYSTEMS Arnold E. Biermann, Fairview Park,Ohio Application May 20, 1957, Serial No. 660,202

15 Claims. (Cl. 123-48) This invention relates to control systems forinternal combustion engines as used for propelling vehicles. Inparticular, the invention refers to control systems for engines whichare used for both propelling and braking or retarding the vehicle and inwhich it is possible to modulate the amount of engine braking.

This invention is particularly applicable for use with variable-strokepiston-type engines in which both engine power and engine braking aremodulated by varying piston stroke. With this type of engine a controlpedal is furnished having a power range, an engine idling range and anengine braking range.

The main objects of the invention are to provide a simple, reliable andlow cost control system. This invention provides a simpler system thanis described in my patent application filed February 20, 1956, Serial566,- 693--because it is unnecessary to sense engine speed and toprovide a fuel shut-off valve.

With a variable-stroke engine it is practical to employ very largedisplacements which provide large amounts of engine braking when thepiston stroke is extended to maximum stroke. The amount of brakingavailable may be too great for sudden application as would result fromremoving the drivers foot from the pedal. Consequently, a further objectof the invention is to improve the ease and safety of driving byproviding an adjustable but fixed amount of engine braking after thecontrol pedal is released.

These and other advantages of this invention will become apparent fromthe following description in which,

Figure 1 is a schematic diagram of one form of the invention.

Figure 2 is a schematic diagram of a second form of the invention.

Figure 3 is a schematic diagram of a third form of the invention.

Figure 4 is a diagram showing a desired variation of the internalcombustion engine 7 with air or a fuel-air I" mixture. The length of thepiston stroke of the engine is varied by angular movement of thestroke-change lever 11 which is forced toward the lever stop 12 by thestrokechange lever spring 13 when the engine is not in operation. Amechanism for varying the stroke of a variable stroke piston engine isfully disclosed in my co-pending application, Serial Number 519,314, nowPatent No. 2,822,791. In Figures 1, 2 and 3, piston stroke is increasedby movement of the stroke-change lever in a clockwise direction. Manualoperation of the control system is provided by pedal 14 which is pivotedon frame 15 by pivot 16.

Pedal 14 is provided with a power range, an engine idling position andan engine braking range as indicated in the figures. Engine idling speedis defined here as the minimum speed that the engine will operatesatisfactorily.

Pedal spring 17 is mounted on the adjusting screw 18 and is arranged toforce pedal 14 into the braking range any desired amount when the pedalis released. For convenience of description it is assumed that pedal 14is operated by a foot of the driver. Foot-free engine braking is definedas the braking provided after the foot is removed from the controlpedal.

Referring now to Figure l, the intake throttle 5 is actuated throughthrottle lever 8 and is urged toward the closed position by spring 9which bears against the stop 10. Throttle lever 8 is actuated from pedal14 through pedal rod 19 and slotted link 20. Lever 8 engages slot 21 oflink 20 through pin 22. Valve lever 23' of the man ifold pressure valve24 is actuated by pin 25 which engages slot 26 of link 20. Valve lever23 is urged toward stop 27 by means of valve lever spring 28.

Engine 7 of Figure 1 is of that type of variable stroke engines in whichengine torque tends to move the strokechange lever 11 to an increasedstroke setting. This movement of 11 is opposed by spring 13. Thus, forevery value of engine torque there is a unique engine piston stroke.Because engine torque is a function of manifold pressure it follows thatas the intake throttle 5 is opened, the resulting increase in enginemean effective pressure increases torque and this increase in torqueserves to increase piston stroke. Therefore, each value of manifoldpressure causes a unique value of piston stroke. The

spring 13 forces the piston stroke to idling value when the throttle 5is practically closed. In the braking range of operation the power forincreasing the piston stroke, with throttle 5 closed, is provided bypiston 29 and slotted connecting rod 30 operating in the servo cylinder31. Servo cylinder 31 is connected with manifold pressure valve 24through tube 32 and valve 24 is connected to the engine manifold 6through tube 33. Cylinder 31 is provided with bleed 34. The idle settingof throttle 5 is modulated according to engine piston stroke by means ofcam 35 which is actuated by the stroke-change lever 11 through rod 36.The cam surface 37 is shaped to open throttle 5 a proper amount tomaintain idling speed at any setting of the stroke-change lever 11.Pivot 38 provides a fill-.- crum for cam 35.

It will be observed that the control system of Figure 1 provides meansfor automatically returning the engine to idling operation whenever thespeed falls to idling value. For example, if the control pedal is in thebraking range and the vehicle encounters an obstacle which reducesengine speed to idling value cam surface 37 will automatically provide athrottle opening such as to cause the engine to idle at that particularpiston stroke setting. At engine speeds greater than idling aninsuflicient amount of fuel mixture will pass through the throttle todevelop any appreciable power. The foregoing construction avoids aby-pass duct around the carburetor as provided in some inventions or thenecessity for shutting off the fuel;

The embodiments of the invention shown in Figures 2 and 3 differ fromthe embodiment of Figure 1 in that power for varying piston stroke issupplied by hydraulic fluid pressure from an outside source for both thepower and the braking ranges, whereas in Figure 1 piston stroke isvaried in the power range by varying engine torque with the inletthrottle and is varied in the braking range by means of reduced manifoldpressure acting on piston 29. In Figures 2 and 3 hydraulic fluid underpressure is supplied to the pressure regulator 39 through tube 40. Thespool valve 42 of the pressure regulator 39 is actuated from the camfollower 41 through spring 47. Discharge from the pressure regulator isprovided by port 65. Stroke-change lever 11 is actuated by piston 43through rod 44. Piston 43 is mounted in servo cylinder 45 which isconnected to the pressure regulator 39 by means of tube 46.

In Figure 2 the cam follower 41 is actuated from pedal 14 by means ofcam link 48 which is mounted for reciprocation in frame 49 ofthepressure regulator. The cam of link 48 consists of a flat portion 55located between the sloping surfaces 56 and 57'. Throttle lever 66 isactuated from cam link 48 by means of spring 50. The idle setting ofthrottle is varied with respect to engine piston stroke by means of cam51 which is actuated by the stroke-change lever 11 through rod 52. Thecam surface 53 is of such shape as to open the throttle 5 a properamount to maintain idling speed at any setting of the stroke of theengine piston. Pivot 5'4 provides a fulcrum for cam 51.

Figure 2 embodies a method of adjusting the amount of foot-free enginebraking from the drivers compartment of a vehicle. In this figure theadjusting screw 18 is turned by means of flexible cable 72 and knob 71.Knob 71 may be mounted on the dash 73 in the drivers compartment.

The embodiment of the invention shown in Figure 3 differs from thatshown in Figure 2 mainly in that at idling position the throttle 5isopen rather than practically closed. In Figure 3 idling isaccomplished by reducing piston stroke to ultra-short values. In Figure3 the cam follower 41 is actuated from pedal 14 by means of cam link 58which is mounted for reciprocation in frame 49. The cam of link 58consists of the two sloping surfaces 59 and 60 which rise to an apex asshown. Throttle 5 is actuated by throttle lever 66 which bears againststop 67 when in the open position. Throttle lever 66 is forced into theopen position when pedal 14 is in the power range by means of pin 68which bears against spring 69. When pedal 14 is in the braking range,pin 70 bears against spring 69 which forces throttle lever 66 againstcam 61. Cam 61 has two cam surfaces 63 and 64. Cam surface 63 is of suchshape as to close the throttle a proper amount to maintain idlingoperation as the control pedal 14 is moved from idling intothe brakingrange. After the throttle is practically closed cam surface 64 providesthe proper relationship between throttle opening and engine pistonstroke to maintain idling operation at any piston stroke should enginespeed fall to idling speed during braking operation.

The general requirements of the control systems described in thisinvention are as follows:

('1) The control system must provide operation with engine piston strokeas short as possible and with throttle as wideopen as possibleconsistent with power requirements.

(2) Whenever the control pedal is in the braking range the controlsystem must provide idling operation if engine speed falls to idlingspeed.

(3). The control system must provide a preselected amount of enginebraking when the control pedal is re-. leased. (Identified as foot-freebraking.)

(4) The. control system must provide means for man: ual adjustment ofthe amount of foot-free braking at some convenient location in the.vehicle.

Figure 4 illustrates, in an. approximate manner, the variationv ofthrottle opening with engine piston stroke for the several forms of the.invention. The operation of that form of the invention illustrated in.Figure l is shown by configuration 1 of. Figure 4. Normal engine idling,as shown at A of Figure 4, is accomplished with an almost closedthrottle and somewhat greater than minimum piston stroke. As power isincreased from idling, the piston stroke remains at idling value, asshown by B, until the throttle is opened to a pre-selected magnitudesuch as C. At this point further opening of the throttle is accompaniedby a corresponding increase in stroke until full throttle and fullstroke are reached; This increase in piston stroke is caused by theincrease in engine torque, obtained by opening the throttle, whichreacts on the stroke-change lever 11 to increase stroke until broughtinto equilibrium by the opposing torque force from spring 13. It will beobserved that spring 13 is pre-loaded so that the stroke-change armremains fixed until torque rises to a pre-selected valve correspondingto the throttle opening at C. As the control pedal is moved from idlinginto the braking range pedal 14 opens valve '24 which serves to increasepiston stroke by utilizing the reduced manifold pressure acting onpiston 29. In this manner piston stroke increases from B to D (Figure4).

During this braking operation throttle 5 is too far closed to provideenough mixture to develop any appreciable rise in the mean effectivepressure of the engine, providing engine speed is greater than idling.If engine speed falls to idling value while pedal 14 is in the brakingrange it is necessary that the throttle opening be adjusted to provideidling cylinder pressures for any piston stroke used; otherwise eithercombustion ceases and the engine stops or the engine runs at faster thanidling speed. This problem is solved by relating throttle opening topiston stroke through cam 35 and rod 36 as shown in Figure l.

The operation of the configuration illustrated by Figure 2 is generallysimilar to that of Figure 1 with the exception that the piston stroke isactuated in both the power and braking ranges by means of hydraulicfluid under pressure from an outside source. The use of hydraulicactuating means in the configuration of Figure 2 permits opening thethrottle to E of Figure 4 before piston stroke starts to increase. Thismethod improves engin efiiciency at part-throttle over that of Figure 1because of the greater amount of operation possible at open throttle andshort stroke. The mechanical efficiency of the engine is greatest Withopen throttle operation;

The operation of the configuration of Figure 2 is as follows: aspedal 14is moved from idling position into the power range link 48 first opensthrottle 5 and then cam surface 57 compresses spring 47 which opens thevalve 42 which in turn supplies hydraulic pressure to cylinder 45 andcauses an increase in piston stroke. It will be observed that spring 13normally forces strokechange lever 11 to minimum stroke. Therefore, forevery hydraulic pressure supplied the servo-cylinder 45 there is aunique piston stroke. Likewise, for every pedal position there is aunique hydraulic pressure and consequently a unique'piston stroke. Aspedal 14 is moved from idle position into the braking range cam surface56 increases the hydraulic pressure and thereby the piston stroke. Atthe same time spring 9 forces throttle lever 66 against cam surface 53.Cam 51 is ac tuated by stroke-change lever 11 and cam surface 53 is ofsuch shape as to insure idling operation if engine speed falls toidling. In Figure 2 it will be observed that the shape of the cam oflink 48 is the same as that of the diagram for piston stroke in Figure4.

The operation of the embodiment of the invention illustrated by Figure3- is generally similar to that of Figure 2 with the exception that thethrottle is substantially open at idling position and the piston strokeis shorter as shown by Figure 4. This arrangement improves engineoperating efiiciencyover that of Figure 2 because of the greater amountof'operation possible at open throttle and short stroke.

The operation of the configuration of Figure 3 is as follows: as pedal14 is moved from the idling position into the power range link 58increases piston stroke with throttle open as shown in- Figure 4. Aspedal 14 is moved from idiinginto the braking range link 58' increasespiston stroke simultaneously as the throttle is closed by cam GI ar-Idspring 69. Dining this movement the throttle opening and the pistonstroke are so related as to provide engine idling operation;shouldengine speed fall to idling speed. A's pedal 14 is moved into thebraking range the throttle falls to minimum opening for idling as thestroke increases to maximum. Cam surface 63 provides idling throttleopening during the transition from open throttle to the low throttleopening of point F of Figure 4 and cam surface 64 provides the correctthrottle opening for the range from F to G.

In all three configurations of this invention a preselected amount offoot-free engine braking is provided by spring 17 which forces pedal 14into the braking range an amount determined by the screw 18. Theprovision of a selected amount of engine braking when the control pedalis released is an important feature of this invention as concerns thesafety and ease with which a vehicle is driven. In present automobileswe have become accustomed to experience the retarding or braking efiectof the engine when the control pedal is released. This braking effectassists in retarding the vehicle before the brakes are applied. In thepast, free-wheeling was found to be unsafe because of the lack of thisautomatic braking. In emergencies, automatic foot-free braking has beenfound highly desirable. In variable stroke engines and in otherarrangements in which it is possible to modulate the amount of enginebraking and in which large amounts of engine braking are possible, thequestion arises as to how much foot-free braking to provide. If thefoot-free engine braking is too great the occupants of the vehicle maybe thrown from their seats during an emergency. On slippery roads it isadvisable to reduce foot-free braking as compared to that provided fordry roads where the traction is good. Excessive braking on slipperyroads can be more dangerous than no braking. One object of thisinvention is to provide means for adjusting the amount of foot-freebraking from the drivers compartment of the vehicle. This objective isaccomplished with a flexible cable and knob as shown in Figure 2. Itwill be observed that this method of controlling foot-free braking alsoapplies to conventional automobile engines in which modulated braking isobtained by throttling the exhaust or by other means.

Each of the three embodiments of this invention described herein hasspecial advantages. The configuration of Figure 1 applies wherehydraulic supply pressure is unavailable or is too costly. Thisarrangement is the least costly, but provides the lowest engineefiiciency of the three. The construction of Figure 3 provides thehighest efliciency but requires an engine with ultra-short stroke. Thedesign of Figure 2 is not as eflicient as that of Figure 3, however theminimum stroke for this arrangement can be quite large.

This invention, as described in the foregoing, is an improvement over myprevious patent application because the necessity for providing specialmeans for cutting off fuel flow during braking and the necessity for anengine speed sensing device are avoided.

While I have described my invention in the foregoing in detail I 'wishit to be understood that many changes may be made therein withoutdeparting from the spirit of the same.

I claim:

1. In a control system for an internal combustion engine having anintake throttle and means for modulating engine braking, a control leverfor controlling said intake throttle and said engine braking, saidcontrol lever having a braking range, means for automatically varyingthe opening of said throttle to cause said engine to operate at idlingspeed when engine speed falls to idling speed whenever said controllever lies in said braking range.

2. In a control system for a variable stroke internal combustion enginehaving an intake manifold throttle and a servo mechanism for varyingpiston stroke for providing modulated engine braking, a control leverfor controlling said servo mechanism having a braking range, means forvarying the opening of said throttle to cause said engine to operate atidling speed when engine speed falls to idling speed whenever saidcontrol lever lies in said braking range.

3. In combination, a variable stroke piston-type internal combustionengine and a control system, a strokechange lever on said engine, anintake manifold throttle, a control lever having a power range, anengine idle position and an engine braking range, means for providingsaid throttle with a preselected variation of opening with respect tothe movement of said stroke-change lever when said control lever lies insaid braking range.

in a control system for a Variable stroke internal combustion enginehaving an intake manifold throttle, a control lever having an engineidle position, a power range and a braking range, means for varyingpiston stroke in said power range and in said braking range, means forvarying said throttle opening prior to variation of piston stroke assaid control lever is moved from said idle position.

5. In a control system for a piston-type internal combustion enginehaving a variable piston stroke, an engine intake throttle, a controllever having a power range, an engine braking range and an idleposition, means for progressively closing said throttle and lengtheningsaid piston stroke as said control lever is moved from said idleposition into said braking range.

6. In a control system for a variable stroke internal combustion enginehaving an intake manifold throttle and a servo mechanism for varying thestroke, a control lever having an engine idle position, a power rangeand an engine braking range, means for actuating said servo mechanism insaid power range and in said braking range, control means for openingsaid throttle when said control lever is moved from said idle positioninto said power range and means for closing said throttle as saidcontrol lever is moved from said idle position into said braking range.

7. In a control system for a variable stroke internal combustion engineequipped with an intake throttle, a control lever having an engine idleposition, a power range and an engine braking range, means forincreasing piston stroke as said control lever is moved from said idleposition into said power range and means for increasing piston stroke assaid control lever is moved from said idle position into said brakingrange, means for opening said throttle as said control lever is movedfrom said idle position into said power range and means forsubstantially closing said throttle as said control lever is moved fromsaid idle position into said braking range.

8. In a control system for an internal combustion engine havingadjustably variable engine braking torque, a foo operated control leverfor actuating said control system, said control lever having a powerrange and an engine braking range, said control lever being pivoted sothat pressure from the toe of the foot forces the control lever intosaid power range, said control lever being pivoted so that pressure fromthe heel of the foot forces the control lever into said engine brakingrange and means for adjustably varying the position of said controllever for the foot-free position.

9. In a control system for an internal combustion engine of the variablepiston stroke type, a manifold throttle, a servo mechanism for varyingthe stroke of said engine, a control lever for controlling said throttleand said servo mechanism, said control lever having a power range, anengine braking range and an engine idle position, means for opening saidthrottle prior to increase of said stroke as said lever is moved fromidle position into said power range.

10. In a control system for a variable stroke internal combustionengine, a manifold throttle, an adjustable stop for controlling theclosing position of said manifold throttle, a control lever foractuating said manifold throttle, a stroke-change lever for varyingpistion stroke, means for actuating said stroke-change lever from saidcontrol lever and linkage means for positioning said adjustablestop as afunction ofthep osition of said stroke-change I lever.

11 Ina control system for. a. piston-type. internal combustion enginehavingamechanism for, automatically increasing, piston stroke. asengine. torque. increases, an. intake manifold-throttle,.a servomechanism for varying.

creasing piston stroke as engine torque. increases. beyond a preselectedmagnitude, anintake manifold with throttle, a control pedal having; anengine idle postion, an engine braking range and an engine power range,means for opening said throttle a preselected amountprior toincrease inpiston stroke as saidcontro-Llever is moved from said idle position intosaid power range and means actuated by reduction of pressure insaidintake manifold for increasing pistonstroke. as. said-control leveris moved from said idle position into said braking. range.

13. In a control system fora variable stroke piston-type internalcombustion engine having. a stroke-change mechanism with springrestraint for returning piston stroke to minimum value While the engineis idling, an engine intake manifold throttle, a controllever having apower range, an engine braking range and an engine idle positio-n,

hydraulic pressure means controlled by said control lever for increasingpiston stroke as said lever is moved from said idle position into saidpower range and as said 8*. lever. ismoved intov said braking range, andmeansvfor varying the. openingof saidthrottle to causethe engine. to.idle when,th'e speed of'said enginefalls to idling during enginebraking, I

14. In. a, control: system for? a: variable stroke internal combustionenginezhaving an intake manifold thrott1c, a control lever having apower range-and a braking ranger, meansfor varying the opening ofsaid.inlet" manifold throttle, means for-varyingsaid piston strokeinsaid-power,- ran-ge and in said braking range, said piston stroke vari--ation extending on either side of a region in, whichsaid, throttle isvaried over substantially the entire throttle open:- ing range.

15. In a control system for a variable stroke internal; combustion.engine, amam'fold throttle, an adjustable; stop; for controlling theclosing. position of said throttle, a con-- trol lever for actuating.said manifold throttle, astroke-r change lever for varying piston,stroke, a stroke-change; valve actuated by said. control lever, pistonmeans for; actuating said stroke-change lever, linkage means-con nectingsaid adjustable stop. with said stroke-change lever: for adjusting. theclosing position of said. throttle as a function of piston stroke, saidstroke-change. valve servingto admit fluid under pressure to said pistonmeans for varying the pistonstrokeofsaidinternal combustion engine.

References Citedin the file of. this patent UNITED- STA-TES PATENT S-1,139.,106 Cutler May 11, 1915- 2,198,247 Grob Apr. 23, 1940 2,433,639Woodrutf et al. Dec. 30, 1947 2,670,724' Reggio Mar. 2, 1954.

